SAE Paper 96 0991, Electrohydraulic Brake Systemxe2x80x94The First Approach to Brake-By-Wire Technology by Wolf-Dieter Jonner, Hermann Winner, Ludwig Dreilich and Eberhardt Schunck, describes a method and a device for controlling a brake system, in which a driver""s intention is determined on the basis of the magnitude of at least one measured signal and implemented by actuating actuator elements at the wheel brakes. This document proposes that the pedal travel and the main cylinder pressure be determined at the brake pedal and the driver""s intention be determined on the basis of this information. In the example described, the driver""s intention is interpreted as a desired deceleration, which is implemented by suitable actuation of the brakes via electrohydraulic valve arrangements.
In order to determine the driver""s intention and the desired values for controlling the wheel brakes from a parameter or a combination of parameters representing a brake pedal actuation, characteristic curves are customarily used. An example thereof is described in German Patent Application No. 195 10 522, where the pedal force and the pedal travel are used as actuation parameters, the braking intention is determined from a combination of these parameters, and desired values for the wheel brakes are determined from the braking intention, taking into account wheel- and axle-specific functions.
It has been found that pure conversion of the actuation parameters, i.e., measured values of the pedal travel, pedal force and/or main cylinder pressure, into a driver""s braking intention results in an unusual response when the driver""s actions are changed. The brakes should, however, be actuated based on the driver""s actions so that the driver can set the desired deceleration in a simple manner with a graduated brake response without first having to learn the behavior of the brake system.
Therefore, an object of the present invention is to improve driver-friendliness and drivability by suitable control of an electrically controlled brake system.
Driver-friendliness and drivability of a vehicle equipped with an electrically controlled brake system is considerably improved because the usual and known behavior of conventional brake systems is emulated by taking into account hysteresis elements in forming the driver""s braking intention as described in the following. This increases the acceptance of an electronically controlled brake system. At the same time, the graduated response of the brake system is improved, which makes it possible to achieve optimum adaptation of the average capability of a driver to control the brake system, which is not possible with a conventional brake system, because the hysteresis characteristics, which are manifested in conventional brake systems due to the mechanical behavior of the elements, can be modified in magnitude and/or form in any desired manner, so that the hysteresis characteristics can be adapted to the desired behavior of the brake system.
It is particularly advantageous that hysteresis is used in converting at least one actuation signal into a driver""s intention signal (desired deceleration, desired braking force, etc.).